1. Field of the Invention
The present invention relates to a finger unit suitable for use in a robot hand that is capable of accurately catching flying objects and the like at high speeds.
2. Description of the Related Art
Finger units for robot hands commonly have an articulated structure, and a high torque actuator that is small, lightweight, and as precise as possible is required for driving each finger joint in order to quickly and reliably perform gripping, picking, and throwing actions with the articulated finger unit.
Such an actuator must include a motor that fits inside the dimensions of the finger, operates at high speed, and can generate high instantaneous maximum output torque; a reduction gear that has minimal backlash with respect at a high reduction gear ratio; and a precision encoder. However, such actuators are not yet commercially available, and there are as yet no related products that could serve as components satisfying such specifications. In other words, the instantaneous maximum output torque of servomotors is insufficient, reduction gears have a large backlash of 1° angle at the output shaft even in the case of multistage planetary types, and there are no encoders that have a sufficiently narrow diameter, low weight, and high resolution.
Examples of prior art that are used to convert the rotation outputted from the rotational output shaft of the actuator in an articulated finger unit into the rotational movement of a perpendicularly oriented joint shaft include screws and rack/pinion combinations, crank mechanisms, worm gears, and wire and sheave systems or the like. With each these options, however, the joint portion acquires excessive dimensions and mass, switching during operation is too slow, and other drawbacks are encountered. The use of a regular bevel gear is problematic from the viewpoint of backlash and smooth rotation.
Conventional fingers mostly have joints that deflect to the inside of the hand in-conjunction with other fingers, and to a large extent it is impossible to perform cooperative work between fingers or to perform various other movements by using such fingers in the palm of a robot hand.
An object of the present invention is to provide a finger unit suitable for use in a robot hand that operates with much greater accuracy and speed than the operating speed of body organs beginning with human visual recognition.